Before scanning, the targeted skin is cooled with a brief burst of compressed air. Infrared images of the target skin are then immediately recorded for two to three minutes. Cancer cells typically reheat more quickly than the surrounding healthy tissue, and this difference can be captured by the infrared camera. Below, doctoral student Muge Pirtini demonstrates how the new scanning system works on a patient. (Credit: Will Kirk/Johns Hopkins)

JOHNS HOPKINS (US)—A new scanning system could take most of the guesswork out of screening a suspect skin growth.

Researchers at Johns Hopkins University are testing a prototype of an infrared scanning system that works by looking for the tiny temperature difference between healthy tissue and a growing tumor.

“The problem with diagnosing melanoma in the year 2010 is that we don’t have any objective way to diagnose this disease,” says Rhoda Alani, adjunct professor at the Johns Hopkins Kimmel Cancer Center and professor and chair of dermatology at the Boston University School of Medicine.

“Our goal is to give an objective measurement as to whether a lesion may be malignant. It could take much of the guesswork out of screening patients for skin cancer.”

The researchers have begun a pilot study with 50 patients. Further patient testing and refinement are needed, but if the system works as envisioned, it could help physicians address a serious health problem.

The National Cancer Institute estimates that 68,720 new cases of melanoma were reported in the United States in 2009; it attributed 8,650 deaths to the disease.

Doctors want to identify a growth that might be skin cancer at an early, treatable stage. They rely now on subjective clues such as the size, shape and coloring of a mole.

With this goal in mind, Alani teamed with heat transfer expert Cila Herman, professor of mechanical engineering in Johns Hopkins’ Whiting School of Engineering.

Three years ago, Herman obtained a $300,000 National Science Foundation grant to develop new ways to detect subsurface changes in temperature.

Her research was aimed at measuring heat differences just below the surface of the skin.

Because cancer cells divide more rapidly than normal cells, they typically generate more metabolic activity and release more energy as heat.

Normally, the temperature difference between cancerous and healthy skins cells is extremely small, so Herman devised a way to make the difference stand out.

First, a patient’s skin is cooled with a harmless one-minute burst of compressed air. Infrared images of the target skin are then immediately recorded for two to three minutes.

Cancer cells typically reheat more quickly than the surrounding healthy tissue, and this difference can be captured by the infrared camera and viewed through sophisticated image processing.

“The system is actually very simple,” Herman says. “An infrared image is similar to the images seen through night-vision goggles.

“In this medical application, the technology itself is noninvasive; the only inconvenience to the patient is the cooling.”

To test the prototype, dermatologist-identified lesions undergo thermal scanning with the new system, and then a biopsy is performed to determine whether melanoma is actually present.

“Obviously, there is a lot of work to do,” Herman says. “We need to fine-tune the instrument—the scanning system and the software—and develop diagnostic criteria for cancerous lesions.

“When the research and refinement are done, we hope to be able to show that our system can find melanoma at an early stage before it spreads and becomes dangerous to the patient.”

“We, at this point, are not able to say that this instrument is able to replace the clinical judgment of a dermatologist, but we envision that this will be useful as a tool in helping to diagnose early-stage melanoma,” Alani says.

“We’re very encouraged about the promise of this technology for improving our ability to prevent people from actually dying of melanoma.”

The researchers envision a hand-held scanning system that dermatologists could use to evaluate suspicious moles.

The technology also might be incorporated into a full-body-scanning system for patients with a large number of pigmented lesions .